<div class="gmail_quote">On Wed, Aug 18, 2010 at 16:52, Matthias Felleisen <<a href="mailto:matthias@ccs.neu.edu">matthias@ccs.neu.edu</a>> wrote: <blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;"> Eduardo is providing a macro that helps you abbreviate complex selector and mutator chains. The BENFIT you get is that instead of writing (posn-x (bird-posn (sky-bird (world-sky some-world)))) you can write -- in Racket -- some-world.sky.bird.posn.x and make Racket programs look as short as C program selectors or Java dots or Javascript dots etc. The PRICE you pay is that you annotate variables and fields with struct information. That is, you have to say somewhere that some-world is a variable that always stands for a world struct. And the sky field in world has to come with information that it always is a sky-struct. And so on. </blockquote></div> As describe in the HelpDesk about `prop:procedure' it is also possible to use the struct id as a procedure, so that it can be used as an accessor/mutator. This is an intermediate solution, as it is nearly (but not quite) as short as the dot notation without introducing global names. Just a quick example that needs more error-checking and needs to be abstracted (and, as Matthias and Shriram are pointing out, this example has a f["baz"] flavor... I don't know if it is possible to fix that if the procedure is not a macro) : #lang racket (struct foo (bar baz) #:mutable #:property prop:procedure (case-lambda [(self attr) (case attr [(bar) (foo-bar self)] [(baz) (foo-baz self)] [else (error "foo: No field named" attr)])] [(self attr val) (case attr [(bar) (set-foo-bar! self val)] [(baz) (set-foo-baz! self val)] [else (error "foo: No field named" attr)])])) (let ([f (foo 1 2)]) (f 'baz 3) (list (f 'bar) (f 'baz))) Laurent